U.S. patent application number 15/269739 was filed with the patent office on 2018-03-22 for chordwise folding and locking of rotor systems.
This patent application is currently assigned to Bell Helicopter Textron Inc.. The applicant listed for this patent is Bell Helicopter Textron Inc.. Invention is credited to Michael Christopher Burnett, Christopher Edward Foskey.
Application Number | 20180079490 15/269739 |
Document ID | / |
Family ID | 61617427 |
Filed Date | 2018-03-22 |
United States Patent
Application |
20180079490 |
Kind Code |
A1 |
Foskey; Christopher Edward ;
et al. |
March 22, 2018 |
Chordwise Folding and Locking of Rotor Systems
Abstract
An apparatus for chordwise folding and locking of rotor systems
includes a grip assembly and a harness disposed at least partially
within and coupled to the grip assembly. A rotor blade is rotatably
coupled to the grip assembly and the harness. The rotor blade has a
radially extended orientation and a stowed orientation. A linkage
assembly has a first end, a second end and a pivot joint
therebetween. The first end of the linkage assembly is rotatably
coupled to the harness and the second end of the linkage assembly
is rotatably coupled to the rotor blade. A first lock assembly
selectively secures the rotor blade to the grip assembly and the
harness when the rotor blade is in the radially extended
orientation. A second lock assembly selectively secures the rotor
blade relative to the harness when the rotor blade is in the stowed
orientation.
Inventors: |
Foskey; Christopher Edward;
(Fort Worth, TX) ; Burnett; Michael Christopher;
(Fort Worth, TX) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Bell Helicopter Textron Inc. |
Fort Worth |
TX |
US |
|
|
Assignee: |
Bell Helicopter Textron
Inc.
Fort Worth
TX
|
Family ID: |
61617427 |
Appl. No.: |
15/269739 |
Filed: |
September 19, 2016 |
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
B64C 29/0033 20130101;
B64C 11/28 20130101; B64C 27/50 20130101 |
International
Class: |
B64C 11/28 20060101
B64C011/28 |
Claims
1. An apparatus for chordwise folding and locking of rotor systems,
the apparatus comprising: a grip assembly; a harness disposed at
least partially within and coupled to the grip assembly; a rotor
blade rotatably coupled to the grip assembly and the harness, the
rotor blade having a radially extended orientation and a stowed
orientation; a linkage assembly having a first end, a second end
and a pivot joint therebetween, the first end rotatably coupled to
the harness and the second end rotatably coupled to the rotor
blade; a first lock assembly selectively securing the rotor blade
to the grip assembly and the harness when the rotor blade is in the
radially extended orientation; and a second lock assembly
selectively securing the rotor blade relative to the harness when
the rotor blade is in the stowed orientation.
2. The apparatus as recited in claim 1 further comprising a pivot
pin coupling the rotor blade to the grip assembly and the
harness.
3. The apparatus as recited in claim 1 wherein the linkage assembly
further comprises first and second tow links rotatably coupled to
the harness, a drag link rotatably coupled to the rotor blade and a
latch pin pivotably coupling the first and second tow links to the
drag link.
4. The apparatus as recited in claim 3 further comprising first and
second bushings respectively rotatably coupling the first and
second tow links to the harness.
5. The apparatus as recited in claim 3 further comprising a linkage
pin rotatably coupling the drag link to the rotor blade.
6. The apparatus as recited in claim 1 wherein the first lock
assembly further comprises a release pin selectively securing the
rotor blade to the grip assembly and the harness when the rotor
blade is in the radially extended orientation.
7. The apparatus as recited in claim 6 wherein the release pin is
removable to allow chordwise folding of the rotor blade relative to
the grip assembly and the harness between the radially extended
orientation and the stowed orientation.
8. The apparatus as recited in claim 6 wherein the release pin is
manually removable to allow chordwise folding of the rotor blade
relative to the grip assembly and the harness between the radially
extended orientation and the stowed orientation.
9. The apparatus as recited in claim 1 wherein the second lock
assembly further comprises a pawl assembly selectively securing the
rotor blade relative to the harness when the rotor blade is in the
stowed orientation.
10. The apparatus as recited in claim 9 wherein the pawl assembly
is disengaged to allow the rotor blade to be released from the
stowed orientation.
11. The apparatus as recited in claim 9 wherein the pawl assembly
is manually disengaged to allow the rotor blade to be released from
the stowed orientation.
12. A method of chordwise folding and locking of rotor systems
including a grip assembly, a harness disposed at least partially
within and coupled to the grip assembly and a rotor blade rotatably
coupled to the grip assembly and the harness, the method
comprising: releasing a first lock selectively securing the rotor
blade to the grip assembly and the harness in a radially extended
orientation; folding the rotor blade chordwise relative to the grip
assembly and the harness from the radially extended orientation to
a stowed orientation while extending a linkage assembly coupled
between the harness and the rotor blade; and securing the rotor
blade in the stowed orientation relative to the harness with a
second lock assembly.
13. The method as recited in claim 12 wherein releasing the first
lock selectively securing the rotor blade to the grip assembly and
the harness in the radially extended orientation further comprises
removing a release pin securing the rotor blade to the grip
assembly and the harness.
14. The method as recited in claim 12 wherein releasing the first
lock selectively securing the rotor blade to the grip assembly and
the harness in the radially extended orientation further comprises
manually removing a release pin securing the rotor blade to the
grip assembly and the harness.
15. The method as recited in claim 12 wherein folding the rotor
blade chordwise relative to the grip assembly and the harness from
the radially extended orientation to the stowed orientation further
comprises manually folding the rotor blade chordwise relative to
the grip assembly and the harness from the radially extended
orientation to the stowed orientation.
16. The method as recited in claim 12 wherein extending the linkage
assembly coupled between the harness and the rotor blade further
comprises pivoting a drag link, rotatably coupled to the rotor
blade, relative to first and second tow links, rotatably coupled to
the harness, about a latch pin.
17. The method as recited in claim 12 wherein securing the rotor
blade in the stowed orientation relative to the harness with the
second lock assembly further comprises engaging a pawl
assembly.
18. The method as recited in claim 12 further comprising: releasing
the second lock assembly; rotating the rotor blade relative to the
grip assembly and the harness from the stowed orientation to the
radially extended orientation while contracting the linkage
assembly coupled between the harness and the rotor blade; and
securing the rotor blade to the grip assembly and the harness in
the radially extended orientation with the first lock assembly.
19. The method as recited in claim 18 wherein releasing the second
lock assembly further comprises disengaging a pawl assembly.
20. The method as recited in claim 18 wherein securing the rotor
blade to the grip assembly and the harness in the radially extended
orientation with the first lock assembly further comprises
inserting a release pin.
Description
TECHNICAL FIELD OF THE DISCLOSURE
[0001] The present disclosure relates, in general, to tiltrotor
aircraft having a VTOL flight mode, a forward flight mode and a
storage mode and, in particular, to chordwise folding and locking
of rotor systems for stowing rotor blades of a tiltrotor aircraft
to reduced the footprint of the tiltrotor aircraft in the storage
mode.
BACKGROUND
[0002] Fixed-wing aircraft, such as airplanes, are capable of
flight using wings that generate lift responsive to the forward
airspeed of the aircraft, which is generated by thrust from one or
more jet engines or propellers. The wings generally have an airfoil
cross section that deflects air downward as the aircraft moves
forward, generating the lift force to support the aircraft in
flight. Fixed-wing aircraft, however, typically require a runway
that is hundreds or thousands of feet long for takeoff and
landing.
[0003] Unlike fixed-wing aircraft, vertical takeoff and landing
(VTOL) aircraft do not require runways. Instead, VTOL aircraft are
capable of taking off, hovering and landing vertically. One example
of a VTOL aircraft is a helicopter which is a rotorcraft having one
or more rotors that provide lift and thrust to the aircraft. The
rotors not only enable hovering and vertical takeoff and landing,
but also enable forward, backward and lateral flight. These
attributes make helicopters highly versatile for use in congested,
isolated or remote areas. Helicopters, however, typically lack the
forward airspeed of fixed-wing aircraft due to the phenomena of
retreating blade stall and advancing blade compression.
[0004] Tiltrotor aircraft attempt to overcome this drawback by
including a set of proprotors that can change their plane of
rotation based on the operation being performed. Tiltrotor aircraft
generate lift and propulsion using proprotors that are typically
coupled to nacelles mounted near the ends of a fixed wing. The
nacelles rotate relative to the fixed wing such that the proprotors
have a generally horizontal plane of rotation in a VTOL flight mode
and a generally vertical plane of rotation in a forward flight
mode, wherein the fixed wing provides lift and the proprotors
provide forward thrust. In this manner, tiltrotor aircraft combine
the vertical lift capability of a helicopter with the speed and
range of fixed-wing aircraft.
[0005] It has been found, however, that tiltrotor aircraft may
occupy a large footprint when not in use, such as during storage on
an aircraft carrier flight deck. Accordingly, certain tiltrotor
aircraft are operable to perform a conversion from flight mode to
storage mode, as seen in prior art FIGS. 1A-1D. In FIG. 1A, a
tiltrotor aircraft is shown in VTOL flight mode with the nacelles
positioned in a generally vertical orientation and with the
proprotors operable for rotation in a generally horizontal plane.
In FIG. 1B, two of the rotor blades of each proprotor have been
folded in the beamwise direction such that all blades are generally
parallel to the wing. In FIG. 1C, the nacelles have been rotated
approximately ninety degrees relative to the wing to a generally
horizontal orientation. In FIG. 1D, the wing has been rotated
approximately ninety degrees relative to the fuselage of the
tiltrotor aircraft such that the wing is generally parallel with
the fuselage. In the illustrated storage mode of the tiltrotor
aircraft, its footprint has been minimized. It has been found,
however, that storing a tiltrotor aircraft with the rotor blades
fully cantilevered to one side of the drive system results in an
undesirably large moment being placed on the drive system, which
may cause damage to bearings or other components of the drive
system. Accordingly, a need has arisen for improved storage modes
for tiltrotor aircraft.
SUMMARY
[0006] In a first aspect, the present disclosure is directed to an
apparatus for chordwise folding and locking of rotor systems. The
apparatus includes a grip assembly and a harness disposed at least
partially within and coupled to the grip assembly. A rotor blade is
rotatably coupled to the grip assembly and the harness. The rotor
blade has a radially extended orientation and a stowed orientation.
A linkage assembly has a first end, a second end and a pivot joint
therebetween. The first end of the linkage assembly is rotatably
coupled to the harness and the second end of the linkage assembly
is rotatably coupled to the rotor blade. A first lock assembly
selectively secures the rotor blade to the grip assembly and the
harness when the rotor blade is in the radially extended
orientation. A second lock assembly selectively secures the rotor
blade relative to the harness when the rotor blade is in the stowed
orientation.
[0007] In some embodiments, a pivot pin may couple the rotor blade
to the grip assembly and the harness. In certain embodiments, the
linkage assembly may include first and second tow links rotatably
coupled to the harness, a drag link rotatably coupled to the rotor
blade and a latch pin pivotably coupling the first and second tow
links to the drag link. In such embodiments, first and second
bushings may respectively rotatably couple the first and second tow
links to the harness and/or a linkage pin may rotatably couple the
drag link to the rotor blade. In some embodiments, a release pin
may selectively secure the rotor blade to the grip assembly and the
harness when the rotor blade is in the radially extended
orientation. In such embodiments, the release pin may be removable,
such as manually removable, to allow chordwise folding of the rotor
blade relative to the grip assembly and the harness between the
radially extended orientation and the stowed orientation. In
certain embodiments, a pawl assembly may selectively secure the
rotor blade relative to the harness when the rotor blade is in the
stowed orientation. In such embodiments, the pawl assembly may
disengaged, such as manually disengaged, to allow the rotor blade
to be released from the stowed orientation.
[0008] In a second aspect, the present disclosure is directed to a
method of chordwise folding and locking of rotor systems that
includes a grip assembly, a harness disposed at least partially
within and coupled to the grip assembly and a rotor blade rotatably
coupled to the grip assembly and the harness. The method includes
releasing a first lock selectively securing the rotor blade to the
grip assembly and the harness in a radially extended orientation;
folding the rotor blade chordwise relative to the grip assembly and
the harness from the radially extended orientation to a stowed
orientation while extending a linkage assembly coupled between the
harness and the rotor blade; and securing the rotor blade in the
stowed orientation relative to the harness with a second lock
assembly.
[0009] The method may also include removing a release pin securing
the rotor blade to the grip assembly and the harness; manually
removing a release pin securing the rotor blade to the grip
assembly and the harness; manually folding the rotor blade
chordwise relative to the grip assembly and the harness from the
radially extended orientation to the stowed orientation; pivoting a
drag link, rotatably coupled to the rotor blade, relative to first
and second tow links, rotatably coupled to the harness, about a
latch pin and/or engaging a pawl assembly. Alternatively or
additionally, the method may include releasing the second lock
assembly; rotating the rotor blade relative to the grip assembly
and the harness from the stowed orientation to the radially
extended orientation while contracting the linkage assembly coupled
between the harness and the rotor blade; and securing the rotor
blade to the grip assembly and the harness in the radially extended
orientation with the first lock assembly. The method may further
include disengaging a pawl assembly and/or inserting a release
pin.
BRIEF DESCRIPTION OF THE DRAWINGS
[0010] For a more complete understanding of the features and
advantages of the present disclosure, reference is now made to the
detailed description along with the accompanying figures in which
corresponding numerals in the different figures refer to
corresponding parts and in which:
[0011] FIGS. 1A-1D are prior art drawings depicting a tiltrotor
aircraft transitioning from a VTOL flight mode to a storage
mode;
[0012] FIGS. 2A-2B are schematic illustrations of an exemplary
tiltrotor aircraft in forward flight mode and in VTOL flight mode
in accordance with embodiments of the present disclosure;
[0013] FIG. 3A is an isometric view of an exemplary propulsion
system for a tiltrotor aircraft in accordance with embodiments of
the present disclosure;
[0014] FIG. 3B is a top view of an exemplary wing section of a
tiltrotor aircraft in accordance with embodiments of the present
disclosure;
[0015] FIGS. 4A-4F are schematic illustrations of an exemplary
tiltrotor aircraft transitioning between VTOL flight mode and
storage mode in accordance with embodiments of the present
disclosure;
[0016] FIGS. 5A-5B are schematic illustrations of a rotor blade in
a radially extended orientation and a stowed orientation in
accordance with embodiments of the present disclosure;
[0017] FIG. 6 is an exploded view of a rotor blade hinging and
locking assembly for manually operating a rotor blade between a
radially extended orientation and a stowed orientation in
accordance with embodiments of the present disclosure;
[0018] FIGS. 7A-7D are top views of a rotor blade hinging and
locking assembly for manually operating a rotor blade between a
radially extended orientation and a stowed orientation in
accordance with embodiments of the present disclosure; and
[0019] FIGS. 8A-8D are side views of a rotor blade hinging and
locking assembly for manually operating a rotor blade between a
radially extended orientation and a stowed orientation in
accordance with embodiments of the present disclosure.
DETAILED DESCRIPTION
[0020] While the making and using of various embodiments of the
present disclosure are discussed in detail below, it should be
appreciated that the present disclosure provides many applicable
inventive concepts, which can be embodied in a wide variety of
specific contexts. The specific embodiments discussed herein are
merely illustrative and do not delimit the scope of the present
disclosure. In the interest of clarity, not all features of an
actual implementation may be described in this specification. It
will of course be appreciated that in the development of any such
actual embodiment, numerous implementation-specific decisions must
be made to achieve the developer's specific goals, such as
compliance with system-related and business-related constraints,
which will vary from one implementation to another. Moreover, it
will be appreciated that such a development effort might be complex
and time-consuming but would be a routine undertaking for those of
ordinary skill in the art having the benefit of this
disclosure.
[0021] In the specification, reference may be made to the spatial
relationships between various components and to the spatial
orientation of various aspects of components as the devices are
depicted in the attached drawings. However, as will be recognized
by those skilled in the art after a complete reading of the present
disclosure, the devices, members, apparatuses, and the like
described herein may be positioned in any desired orientation.
Thus, the use of terms such as "above," "below," "upper," "lower"
or other like terms to describe a spatial relationship between
various components or to describe the spatial orientation of
aspects of such components should be understood to describe a
relative relationship between the components or a spatial
orientation of aspects of such components, respectively, as the
device described herein may be oriented in any desired
direction.
[0022] Referring to FIGS. 2A-2B in the drawings, a tiltrotor
aircraft is schematically illustrated and generally designated 10.
Aircraft 10 includes a fuselage 12, a wing mount assembly 14 that
is rotatable relative to fuselage 12 and a tail assembly 16
including rotatably mounted tail members 16a, 16b having control
surfaces operable for horizontal and/or vertical stabilization
during forward flight. A wing member 18 is supported by wing mount
assembly 14 and rotates with wing mount assembly 14 relative to
fuselage 12 as discussed herein. Located at outboard ends of wing
member 18 are propulsion assemblies 20a, 20b. Propulsion assembly
20a includes a nacelle depicted as fixed pylon 22a that houses an
engine and transmission. In addition, propulsion assembly 20a
includes a mast assembly 24a that is rotatable relative to fixed
pylon 22a between a generally horizontal orientation, as best seen
in FIG. 2A, a generally vertical orientation, as best seen in FIG.
2B. Propulsion assembly 20a also includes a proprotor assembly 26a
that is rotatable relative to mast assembly 24a responsive to
torque and rotational energy provided via a rotor hub assembly and
drive system mechanically coupled to the engine and transmission.
Likewise, propulsion assembly 20b includes a nacelle depicted as
fixed pylon 22b that houses an engine and transmission, a mast
assembly 24b that is rotatable relative to fixed pylon 22b and a
proprotor assembly 26b that is rotatable relative to mast assembly
24b responsive to torque and rotational energy provided via a rotor
hub assembly and drive system mechanically coupled to the engine
and transmission.
[0023] FIG. 2A illustrates aircraft 10 in airplane or forward
flight mode, in which proprotor assemblies 26a, 26b are rotating in
a substantially vertical plane to provide a forward thrust enabling
wing member 18 to provide a lifting force responsive to forward
airspeed, such that aircraft 10 flies much like a conventional
propeller driven aircraft. FIG. 2B illustrates aircraft 10 in
helicopter or VTOL flight mode, in which proprotor assemblies 26a,
26b are rotating in a substantially horizontal plane to provide a
lifting thrust, such that aircraft 10 flies much like a
conventional helicopter. It should be appreciated that aircraft 10
can be operated such that proprotor assemblies 26a, 26b are
selectively positioned between forward flight mode and VTOL flight
mode, which can be referred to as a conversion flight mode. Even
though aircraft 10 has been described as having one engine in each
fixed pylon 22a, 22b, it should be understood by those having
ordinary skill in the art that other engine arrangements are
possible and are considered to be within the scope of the present
disclosure including, for example, having a single engine which may
be housed within the fuselage that provides torque and rotational
energy to both proprotor assemblies 26a, 26b.
[0024] In the illustrated embodiment, proprotor assemblies 26a, 26b
each include three twisted rotor blades that are equally spaced
apart circumferentially at approximately 120 degree intervals. It
should be understood by those having ordinary skill in the art,
however, that proprotor assemblies 26a, 26b of the present
disclosure could have rotor blades with other designs and other
configurations. During flight modes, proprotor assemblies 26a, 26b
rotate in opposite directions to provide torque balancing to
aircraft 10. For example, when viewed from the front of aircraft 10
in forward flight mode, proprotor assembly 26a rotates clockwise
and proprotor assembly 26b rotates counterclockwise. In addition,
proprotor assemblies 26a, 26b rotate in phase with each other such
that the rotor blades of each proprotor assembly 26a, 26b pass wing
member 18 at the same time during all modes of operation of
aircraft 10. Further, as discussed herein, proprotor assemblies
26a, 26b are mechanically coupled to a common interconnect drive
shaft such that proprotor assemblies 26a, 26b have matched counter
rotation wherein any rotation of one proprotor assembly 26a, 26b
results in an equal counter rotation of the other of proprotor
assembly 26a, 26b.
[0025] Referring now to FIGS. 3A-3B, propulsion assembly 20a is
disclosed in further detail. Propulsion assembly 20a is
substantially similar to propulsion assembly 20b therefore, for
sake of efficiency, certain features will be disclosed only with
regard to propulsion assembly 20a. One having ordinary skill in the
art, however, will fully appreciate an understanding of propulsion
assembly 20b based upon the disclosure herein of propulsion
assembly 20a. Propulsion assembly 20a includes an engine 30 that is
fixed relative to wing 18. An engine output shaft 32 transfers
power from engine 30 to a spiral bevel gearbox 34 that includes
spiral bevel gears to change torque direction by 90 degrees from
engine 30 to a fixed gearbox 36 via a clutch. Fixed gearbox 36
includes a plurality of gears, such as helical gears, in a gear
train that are coupled to an interconnect drive shaft 38 and a
quill shaft (not visible) that supplies torque to an input in
spindle gearbox 40 of proprotor gearbox 42.
[0026] Interconnect drive shaft 38 provides a torque path that
enables a single engine of aircraft 10 to provide torque to both
proprotors 26a, 26b in the event of a failure of the other engine.
In the illustrated embodiment, interconnect drive shaft 38 has a
rotational axis 44 that is aft of a conversion axis 46 of spindle
gearbox 40. Conversion axis 46 is parallel to a lengthwise axis 48
of wing 18. In the illustrated embodiment, interconnect drive shaft
38 includes a plurality of segments that share common rotational
axis 44. The location of interconnect drive shaft 38 aft of wing
spar 50 provides for optimal integration with fixed gearbox 36
without interfering with the primary torque transfer in the quill
shaft between fixed gearbox 36 and spindle gearbox 40.
[0027] Engine 30 is housed and supported in fixed pylon 22a (see
FIGS. 2A-2B) that may include features such as an inlet,
aerodynamic fairings and exhaust, as well as other structures and
systems to support and facilitate the operation of engine 30.
Proprotor 26a of propulsion assembly 20a includes three rotor
blades 52a, 52b, 52c that are hingeably coupled to grip assemblies
of a rotor hub 54. Rotor hub 54 is coupled to a mast 56 that is
coupled to proprotor gearbox 42. Together, spindle gearbox 40,
proprotor gearbox 42 and mast 56 are part of mast assembly 24a that
rotates relative to fixed pylon 22a. In addition, it should be
appreciated by those having ordinary skill in the art that mast
assembly 24a may include different or additional components, such
as a pitch control assembly depicted as swashplate 58, actuators 60
and pitch links 62, wherein swashplate 58 is selectively actuated
by actuators 60 to selectively control the collective pitch and the
cyclic pitch of rotor blades 52a, 52b, 52c via pitch links 62. A
linear actuator, depicted as conversion actuator 64 of fixed pylon
22a, is operable to reversibly rotate mast assembly 24a relative to
fixed pylon 22a, which in turn selectively positions proprotor
assembly 26a between forward flight mode, in which proprotor
assembly 26a is rotating in a substantially vertical plane, and
VTOL flight mode, in which proprotor assembly 26a is rotating in a
substantially horizontal plane.
[0028] Referring next to FIGS. 4A-4F of the drawings, tiltrotor
aircraft 10 is depicted in various states during a transition
between VTOL flight mode and storage mode. Aircraft 10 has a VTOL
flight mode, as best seen in FIG. 2B, a forward flight mode, as
best seen in FIG. 2A, and a storage mode, as best seen in FIG. 4F.
As discussed above, aircraft 10 includes fuselage 12 and wing 18
that is rotatably mounted to fuselage 12. Wing 18 is reversibly
rotatable between a flight orientation that is generally
perpendicular to fuselage 12, as best seen in FIG. 4A, and a stowed
orientation that is generally parallel to fuselage 12, as best seen
in FIG. 4F. Pylon assemblies 22a, 22b are positioned proximate the
outboard ends of wing 18. Mast assemblies 24a, 24b are respectively
rotatable relative to pylon assemblies 22a, 22b. Mast assemblies
24a, 24b are reversibly rotatable between a generally vertical
orientation, as best seen in FIG. 4A, and a generally horizontal
orientation, as best seen in FIGS. 4B-4F. Proprotor assemblies 90a,
90b are respectively rotatable relative to mast assemblies 24a,
24b. Proprotor assembly 90a includes rotor blades 92a, 92b, 92c and
proprotor assembly 90b includes rotor blades 92d, 92e, 92f.
Proprotor assemblies 90a, 90b each have a radially extended
orientation, as best seen in FIG. 4A, and a stowed orientation, as
best seen in FIG. 4F. More specifically in the stowed orientation,
rotor blade 92a of proprotor assembly 90a is folded chordwise below
wing 18 and generally conforming with pylon assembly 22a and rotor
blade 92d of proprotor assembly 90b is folded chordwise below wing
18 and generally conforming with pylon assembly 22b. Rotor blade
92b of proprotor 90a is folded chordwise above wing 18 and
generally conforming with pylon assembly 22a and rotor blade 92e of
proprotor 90b is folded chordwise above wing 18 and generally
conforming with pylon assembly 22b. Rotor blade 92c of proprotor
90a is inboardly extended generally parallel with wing 18 and rotor
blade 92f of proprotor 90b is inboardly extended generally parallel
with wing 18.
[0029] An example conversion operation of aircraft 10 from VTOL
flight mode to storage mode will now be described, wherein folding
of the rotor blades is preferably accomplished using a manual
process. In FIG. 4A, aircraft 10 is best characterized as being in
VTOL flight mode. As illustrated, wing 18 is in flight orientation,
generally perpendicular to fuselage 12. Mast assemblies 24a, 24b
are each in a generally vertical orientation. Proprotor assemblies
90a, 90b are each in a radially extended orientation. Tail members
16a, 16b are in a dihedral orientation. Rotor blades 92a, 92b, 92c
have been collectively operated to have a generally vertical or
feathered orientation. Rotor blades 92d, 92e, 92f have been
collectively operated to have a generally vertical or feathered
orientation. In FIG. 4B, the conversion from VTOL flight mode to
storage mode has begun. As illustrated, wing 18 remains in flight
orientation, generally perpendicular to fuselage 12. Mast
assemblies 24a, 24b have rotated approximately 90 degrees to the
horizontal orientation. Tail members 16a, 16b remains in the
dihedral orientation. Rotor blades 92a, 92b, 92c remain radially
extended. Rotor blades 92d, 92e, 92f remains radially extended.
Proprotor assemblies 90a, 90b are positioned such that rotor blade
92b and rotor blade 92e each has a generally upwardly extending
vertical orientation.
[0030] In FIG. 4C, the conversion from VTOL flight mode to storage
mode continues. As illustrated, wing 18 remains in flight
orientation, generally perpendicular to fuselage 12. Mast
assemblies 24a, 24b are in the horizontal orientation. Tail members
16a, 16b remains in the dihedral orientation. Rotor blades 92a, 92d
have been manually unlocked and partially folded to manually
maintain ground clearance and clearance with pylon assemblies 22a,
22b. Rotor blades 92b, 92c, 92e, 92f remain radially extended. In
FIG. 4D, the conversion from VTOL flight mode to storage mode
continues. As illustrated, wing 18 remains in flight orientation,
generally perpendicular to fuselage 12. Mast assemblies 24a, 24b
are in the horizontal orientation. Tail members 16a, 16b remains in
the dihedral orientation. Proprotor assemblies 90a, 90b have
counter rotated approximately 30 degrees such that rotor blades
92c, 92f are inboardly extending generally parallel with wing 18.
Rotor blades 92a, 92d are now clear of pylon assemblies 22a, 22b
and are folded and locked in a stowed orientation. Rotor blades
92b, 92c, 92e, 92f remain radially extended.
[0031] In FIG. 4E, the conversion from VTOL flight mode to storage
mode continues. As illustrated, wing 18 remains in flight
orientation, generally perpendicular to fuselage 12. Mast
assemblies 24a, 24b are in the horizontal orientation. Tail members
16a, 16b remains in the dihedral orientation. Rotor blade 92a is in
a stowed orientation beneath wing 18 and generally conforming with
pylon assembly 22a. Rotor blade 92d is in a stowed orientation
beneath wing 18 and generally conforming with pylon assembly 22b.
Rotor blade 92b has been manually unlocked, folded and locked in a
stowed orientation above wing 18 and generally conforming with
pylon assembly 22a. Rotor blade 92e has been manually unlocked,
folded and locked in a stowed orientation above wing 18 and
generally conforming with pylon assembly 22b. Rotor blades 92c, 92f
are each inboardly extending generally parallel with wing 18. In
FIG. 4F, the conversion from VTOL flight mode to storage mode is
complete. As illustrated, wing 18 has been rotated approximately 90
degrees to a stowed orientation, generally parallel to fuselage 12.
Mast assemblies 24a, 24b are in the horizontal orientation. Tail
members 16a, 16b are fully lowered to an anhedral orientation.
Rotor blade 92a is in a stowed orientation beneath wing 18 and
generally conforming with pylon assembly 22a. Rotor blade 92d is in
a stowed orientation beneath wing 18 and generally conforming with
pylon assembly 22b. Rotor blade 92b is in a stowed orientation
above wing 18 and generally conforming with pylon assembly 22a.
Rotor blade 92e is in a stowed orientation above wing 18 and
generally conforming with pylon assembly 22b. Rotor blades 92c, 92f
are each inboardly extending generally parallel with wing 18 in a
stowed orientation.
[0032] As illustrated, the storage mode of aircraft 10 depicted and
described with reference to FIGS. 4A-4F significantly reduces the
footprint of aircraft 10 as compared to the flight modes of
aircraft 10. In the illustrated storage mode of aircraft 10, the
stowed orientation of the rotor blades does not result in an
undesirably large moment being placed on the drive systems. To
return aircraft 10 from storage mode to VTOL flight mode, a reverse
sequence may be followed to avoid contact between the various
components of aircraft 10 with each other as well as to avoid
contact between the various components of aircraft 10 and the
surface on which aircraft 10 rests.
[0033] Referring to FIGS. 5A-8D, the chordwise folding operation of
a rotor blade is more fully described. The hingable relationship of
rotor blade 92a to rotor hub 94a is substantially similar to the
hingable relationship between each rotor blade and the respective
rotor hub therefore, for sake of efficiency, certain features will
be disclosed only with regard to rotor blade 92a and rotor hub 94a.
One having ordinary skill in the art, however, will fully
appreciate an understanding of the hingable relationship between
other rotor blades and rotor hubs based upon the disclosure herein
of rotor blade 92a and rotor hub 94a. In the illustrated portions,
rotor hub 94a includes a pitch horn 100, a leading fairing 102 and
a trailing fairing 104, as best see in FIGS. 5A-5B. In addition,
rotor hub 94a includes a grip assembly 106 and a harness 108 that
are coupled together with connectors 110a, 110b along axis 112, as
best seen in FIG. 6. It is noted that there are two instances of
axis 112 labeled in FIG. 6, which symbolize that the instance of
axis 112 extending through grip assembly 106 and the instance of
axis 112 extending through harness 108 are a common axis when rotor
hub 94a is fully assembled, wherein harness 108 is at least
partially disposed within grip assembly 106. It is accordingly to
be understood by those having ordinary skill in the art that this
common axis convention will be used throughout FIG. 6.
[0034] Rotor blade 92a is rotatably coupled to grip assembly 106
and harness 108 about pivot pin 116 that extends along axis 114. In
the illustrated embodiment, spacers 118a, 118b are sandwiched
between grip assembly arms 106a, 106b and harness 108 along axis
114 and grip assembly arms 106a, 106b are sandwiched between blade
tangs 120a, 120b such that pivot pin 116 passes through blade tang
120a, grip assembly arm 106a, spacer 118a, harness 108, spacer
118b, grip assembly arm 106b and blade tang 120b. A nut 122 is
threadably coupled to pivot pin 116 to secure rotor blade 92a, grip
assembly 106 and harness 108 together. Rotor blade 92a is secured
in the radially extended orientation, as best seen in FIGS. 5A, 7A
and 8A, by a lock assembly depicted as release pin 124 that extends
along axis 126. In the illustrated embodiment, bushings 128a, 128b
are sandwiched between grip assembly arms 106a, 106b and harness
108 along axis 126 and grip assembly arms 106a, 106b are sandwiched
between blade tangs 120a, 120b such that release pin 124 passes
through blade tang 120a, grip assembly arm 106a, bushing 128a,
harness 108, bushing 128b, grip assembly arm 106b and blade tang
120b. A nut 130 is threadably coupled to release pin 124 to prevent
rotor blade 92a from rotating relative to grip assembly 106 and
harness 108 when rotor blade 92a is in the radially extended
orientation for flight modes of aircraft 10.
[0035] A linkage assembly 132 is rotatably coupled to harness 108
and is rotatably coupled to rotor blade 92a. Linkage assembly 132
includes tow links 134a, 134b, a latch pin 136 and a drag link 138.
In the illustrated embodiment, tow links 134a, 134b are rotatable
about axis 126 as tow links 134a, 134b are respectively positioned
on bearing surfaces 140a, 104b of bushings 128a, 128b. Tow links
134a, 134b rotatably coupled to drag link 138 via latch pin 136
along axis 142. More specifically, tow links 134a, 134b are
sandwiched between drag link arms 138a, 138b with latch pin 136
extending therethrough. Drag link 138 is rotatably coupled to rotor
blade 92a by linkage pin 144. In the illustrated embodiment, drag
link 138 is sandwiched between spacers 148a, 148b and between blade
tangs 120a, 120b such that linkage pin 144 passes through blade
tang 120a, spacer 148a, drag link 138, spacer 148b and blade tang
120b. A nut 150 is threadably coupled to linkage pin 144 to secure
rotor blade 92a and drag link 138 together. Rotor blade 92a is
secured in the stowed orientation, as best seen in FIGS. 5B, 7D and
8D, by a lock assembly depicted as pawl assembly 152. Pawl assembly
152 includes a pawl member 152a that is coupled to harness 108 by
pin 154a in receiving region 156 of harness 108. Pawl assembly 152
also includes a pawl member 152b that is coupled to harness 108 by
pin 154b in receiving region 158 of pawl member 152a and receiving
region 156 of harness 108.
[0036] The operation of chordwise folding and locking of rotor
blade 92a will now be described. As best seen in FIGS. 7A and 8A,
rotor blade 92a is secured to grip assembly 106 and harness 108 in
the radially extended orientation by pivot pin 116 and release pin
124. This configuration of rotor blade 92a relative to grip
assembly 106 and harness 108 is used for flight modes of tiltrotor
aircraft 10. When it is desired to convert aircraft 10 to storage
mode, rotor blade 92a is folded chordwise relative to grip assembly
106 and harness 108. As a first step, release pin 124 is removed
from its connection with rotor blade 92a, grip assembly 106 and
harness 108, which may be a manual process. In this configuration,
rotor blade 92a is operable to rotate about pivot pin 116 relative
to grip assembly 106 and harness 108, which may be a manual
process. As best seen in FIGS. 7B and 8B, rotor blade 92a has
rotated approximately 20 degrees relative to grip assembly 106 and
harness 108. It is noted that linkage assembly 132 is moving from a
contracted orientation to an extended orientation as rotor blade
92a rotates relative to grip assembly 106 and harness 108. The
extension of linkage assembly 132 is a result of tow links 134a,
134b rotating about bearing surfaces 140a, 104b of bushings 128a,
128b, which remain coupled to harness 108 without the requirement
of release pin 124 extending therethrough.
[0037] As best seen in FIGS. 7C and 8C, rotor blade 92a has rotated
approximately 70 degrees relative to grip assembly 106 and harness
108 as linkage assembly 132 continues to be extended between rotor
blade 92a and harness 108. In addition, latch pin 136 of linkage
assembly 132 is approaching pawl assembly 152. As best seen in
FIGS. 7D and 8D, rotor blade 92a has rotated approximately 90
degrees relative to grip assembly 106 and harness 108 as linkage
assembly 132 continues to be extended between rotor blade 92a and
harness 108. Rotor blade 92a is now in the stowed orientation. In
addition, latch pin 136 of linkage assembly 132 has engaged pawl
assembly 152, which now locks rotor blade 92a in the stowed
orientation relative to the harness 108. More specifically, as
latch pin 136 of linkage assembly 132 engages pawl assembly 152,
latch pin 136 passes across pawl member 152b and enters a receiving
region 160 of harness 108. Once latch pin 136 enters region 160,
pawl member 152b prevent latch pin 136 from exiting region 160 and
thus locks rotor blade 92a in the stowed orientation relative to
the harness 108.
[0038] When it is desired to return aircraft 10 to flight mode,
rotor blade 92a is unfolded chordwise relative to grip assembly 106
and harness 108. As a first step, pawl member 152a is depressed to
eject latch pin 136 from region 160 of harness 108, which may be a
manual process. In this configuration, rotor blade 92a is operable
to rotate about pivot pin 116 relative to grip assembly 106 and
harness 108 such that rotor blade 92a may be returned to the
radially extended orientation, which may be a manual process. It is
noted that linkage assembly 132 is moving from the extended
orientation to the contracted orientation as rotor blade 92a
rotates relative to grip assembly 106 and harness 108. Once rotor
blade 92a is in the radially extended orientation, release pin 124
may be reinserted through blade tang 120a, grip assembly arm 106a,
bushing 128a, harness 108, bushing 128b, grip assembly arm 106b and
blade tang 120b. Nut 130 may now be threadably coupled to release
pin 124 to secure rotor blade 92a in the radially extended
orientation for flight modes of aircraft 10.
[0039] The foregoing description of embodiments of the disclosure
has been presented for purposes of illustration and description. It
is not intended to be exhaustive or to limit the disclosure to the
precise form disclosed, and modifications and variations are
possible in light of the above teachings or may be acquired from
practice of the disclosure. The embodiments were chosen and
described in order to explain the principals of the disclosure and
its practical application to enable one skilled in the art to
utilize the disclosure in various embodiments and with various
modifications as are suited to the particular use contemplated.
Other substitutions, modifications, changes and omissions may be
made in the design, operating conditions and arrangement of the
embodiments without departing from the scope of the present
disclosure. Such modifications and combinations of the illustrative
embodiments as well as other embodiments will be apparent to
persons skilled in the art upon reference to the description. It
is, therefore, intended that the appended claims encompass any such
modifications or embodiments.
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